To convey granular material with sharp corners through a pipe line via a compressed-gas carrier, requires the material to be fed to the gas stream as discrete granules through a relatively small opening, for metering, which can be blocked if the fed material becomes entangled or lumpy. Such trouble is inherent in the case of granular material having sharp corners, the sharp corners causing the granules to interlock. Such blockage prevents continuous uniform feeding of the material into the gas stream carrier flowing through the conveyor pipe line.
Such granules particularly tend to form lumps when compressed together as they must be to force them into the conveyor pipe line, as by providing a supply of the granular material above the pipe line for gravity feeding.
A supply of such granular material with the granules flowing freely, carried by the compressed-gas carrier, is desirable for various purposes, such as use in connection with sand-blasting techniques. For example, contaminated surfaces of nuclear reactor components may be cleaned by this technique, using sharp cornered granules of B.sub.2 O.sub.3, the lumping problem described above being in this instance complicated by the fact that such granules are hydroscopic, increasing the tendency for the granules to clump together and form lumps which cannot be continuously fed into a compressed-gas carrier flowing through a conveyor pipe line. However, other materials also cause trouble, examples being sharp cornered granules of boron carbide, carborundum, quartz and metallic particles such as chips resulting from machining operations.
The object of the present invention is to provide an apparatus for satisfactorily feeding such granular material into a gas-carrier stream flowing through a conveyor pipe line.